A new study suggests that dinosaurs may not have been in decline before the asteroid wiped them out 66 million years ago. The research, published in Current Biology, analyzed the fossil record of North America over 18 million years and found that the quality of the record worsens during the final six million years prior to the asteroid impact.
The study’s lead author, Dr Chris Dean, said that if taken at face value, the fossil record suggests that dinosaurs peaked around 75 million years ago and then declined. However, the research team found that this trend is due to fossils from that time being less likely to be discovered.
Instead, they suggest that dinosaurs may have been doing better than previously suggested in the lead-up to the asteroid impact. The study found that the proportion of land occupied by four dinosaur types remained constant overall, suggesting their potential habitat area remained stable and risk of extinction stayed low.
The researchers also found that Ceratopsian dinosaurs, such as Triceratops, were more likely to be detected later on in this period, occupying more areas. This was due to these dinosaurs favoring green plains away from rivers at a time when this kind of habitat became the main type of environment being preserved.
The study’s findings challenge the long-held idea that dinosaurs were doomed before the asteroid impact. Instead, it suggests that they may have had a higher diversity of species and could have survived with mammals, lizards, and their surviving descendants: birds.
Source: https://www.ucl.ac.uk/news/2025/apr/dinosaurs-apparent-decline-prior-asteroid-may-be-due-poor-fossil-record